The present invention relates generally to electric vehicles and, more particularly, to a system and method for controlling a surface-mounted permanent magnet synchronous machine drive used in electric vehicles over a wide speed range using a reference voltage.
The assignee of the present invention designs and develops electric vehicles employing surface-mounted permanent magnet synchronous machine drives. One operation that is required when controlling such machine drives is flux weakening, which is when the machine drive operates above base speed.
One straight-forward approach is to employ a number of look-up tables to resolve flux weakening operation. In order to achieve results and performance similar to those of the present invention, the straight-forward approach mentioned above requires creation of numerous and cumbersome data structures, such as look-up tables, to handle all possible situations in the system and its environment.
A method presented in a paper authored by J. H. Song, J. M. Kim and S. K. Sul, entitled "A New Robust SPMSM Control to Parameter Variations in Flux Weakening Region", in Proc. IECON'96, pp. 1193-1198, 1996, attempts to provide a solution to the problem solved by the present invention. The Song et al. approach requires measurement of DC bus voltage.
It would be desirable to have a method that does not rely on look-up up tables and wherein automatic transition is accomplished at any operating conditions. It would also be desirable to have a method that does not require measurement of the DC bus voltage.
It is, therefore, an objective to provide for a system and method for controlling a surface-mounted permanent magnet synchronous machine drive over a wide speed range using a reference voltage. It is also an objective to provide for a system and method for controlling a surface-mounted permanent magnet synchronous machine drive used in electric vehicles.